Streptococcus pneumoniae is a leading cause of pneumonia. According to 2010 Mortality Trend by Cause published by The National Statistical Office, pneumonia was one of the top 10 causes of death, with 14.9 deaths per 100,000 people, which is an 82.9% increase from 2000. The World Health Organization (WHO) also estimated in 2012 that globally, 476,000 HIV negative children younger than 5 years of age died from infection by Streptococcus pneumoniae, which accounts for 5% of all-cause child mortality for children under five.
In 1977, Dr. Robert Austrian developed a 14-valent pneumococcal polysaccharide vaccine in order to prevent pneumococcal disease and then the vaccine evolved to a 23-valent polysaccharide vaccine. The multivalent pneumococcal polysaccharide vaccines have proved valuable in preventing pneumococcal disease in elderly adults and high-risk patients. However, infants and young children respond poorly to most pneumococcal polysaccharides due to T-cell independent immune response. The 7-valent pneumococcal conjugate vaccine (7vPnC, Prevnar®) contains the capsular polysaccharides from the seven most prevalent serotypes 4, 6B, 9V, 14, 18C, 19F and 23F. Since approved in the U.S. in 2000, Prevnar has been demonstrated to be highly immunogenic and effective against invasive disease and otitis media in infants and young children. This vaccine is now approved in about 80 countries around the world. Prevnar covers approximately 80-90%, 60-80%, and 40-80% of invasive pneumococcal disease (IPD) in the US, Europe, and other regions of the world, respectively. As expected, surveillance data gathered in the years following Prevnar's introduction has clearly demonstrated a reduction of invasive pneumococcal disease caused by the serotypes covered by Prevnar in the US. However, the coverage of the serotypes was limited in some regions and invasive pneumococcal diseases caused by the serotypes that are not covered by Prevnar, in particular 19A, have increased.
The Advisory Committee on Immunization Practices (ACIP) announced in February, 2010 its recommendation of a newly approved 13-valent pneumococcal conjugate vaccine (PCV-13) for vaccination. PCV-13 is a pneumococcal conjugate vaccine comprising six additional serotypes (1, 3, 5, 6A, 7F, 19A) in addition to the seven serotypes (4, 6B, 9V, 14, 18C, 19F, 23F) comprised in Prevnar. According to US Active Bacterial Core surveillance (ABCs), a total of 64% in the IPD cases known as the pathogenic serotypes among children of younger than 5 years of age is covered by PCV-13. In 2007, only 70 cases among 4600 IPDs in children younger than 5 years of age were covered by PCV7, while 2900 cases were covered by PCV-13, which accounts for the majority. Now, a 15-valent pneumococcal conjugate vaccine is under development which covers additional serotypes whose incidence increases with serotype replacement.